I'm working on a planet with 75% of Earth's gravity, and I'm wondering how to get a stable climate despite the thinner atmosphere. I know a thinner atmosphere doesn't trap heat well, so the temperature differences between the night and day and between summer and winter might be more extreme. If I had the atmospheric pressure at 0.8 atm but covered the planet in 80% ocean, would that proportionally larger ocean possibly serve to keep the planet at a more stable temperature? Might it decrease the temperature difference between the poles and the equator? I know that the ocean is also a carbon sink, so I'd also like to avoid plunging the planet into an ice age.
Winds reach all parts of land and sea
In hot area (land or sea), air heats up, expands, raises up and lets cold air blow from sides. This causes sea breeze, land breeze, winds etc. to regulate temperature. With thin atmosphere, regulation effect is less.
Sea water regulates temperature in coastal ares only
Specific heat capacity of water is high which is helpful in regulating temperature. Also there are hot and cold ocean currents. But they are effective in coastal areas or small islands only. Deep inside big continents, hot ares will be more hot and cold ares will be more cold.
Reception of heat from Sun
If the planet is receiving enough heat from its Sun, then there is no worry of ice age. As told here:
The onset of an ice age is related to the Milankovitch cycles - where regular changes in the Earth's tilt and orbit combine to affect which areas on Earth get more or less solar radiation.
When all these factors align so the northern hemisphere gets less solar radiation in summer, an ice age can be started.